Ruby IO streams can be set to nonblock by using the fcntl library and calling IO#fcntl as shown below:

require 'fcntl'

# get current flags
flags = write.fcntl(Fcntl::F_GETFL)

# set O_NONBLOCK flag
write.fcntl(Fcntl::F_SETFL, flags | (Fcntl::O_NONBLOCK)) 

# clear O_NONBLOCK flag
write.fcntl(Fcntl::F_SETFL, flags & (~Fcntl::O_NONBLOCK))

Our logic should be calling the NIO setBlocking with true when O_NONBLOCK flag is zero and with false when O_NONBLOCK is nonzero, but we have it reversed:

This is obviously wrong, but inconveniently also messes up the workaround for #8069.